html,
body {
  min-height: 100vh;
  width: 100vw;
  overflow: hidden;
}
img {
  max-width: 100%;
}
body {
  background: #56ccf2;
  /* fallback for old browsers */
  background: -webkit-linear-gradient(to right, #2f80ed, #56ccf2);
  /* Chrome 10-25, Safari 5.1-6 */
  background: linear-gradient(to right, #2f80ed, #56ccf2);
  /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
}
pre {
  background-color: #f2f2f2;
  padding: 15px;
  font-size: 14px;
  font-family: Consolas;
}
.board {
  position: absolute;
  z-index: 1;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 800px;
  min-height: 600px;
  border-radius: 3px;
  background-color: #fff;
  padding: 20px;
  box-sizing: border-box;
}
.board > .board-title {
  text-align: center;
  font-size: 40px;
}
.board > .board-content {
  padding: 15px 0px;
}
.board > .board-content .example-dom {
  text-align: center;
  padding-top: 50px;
  color: #888;
}
